Lubricating greases thickened with soaps obtained by alkali fusion of amino alcohols



LUBRICATING GREASES THICKENED WITH SOAPS OBTAINED BY ALKALI FUSION OFAMINO ALCOHOLS A rnold J. Morway, Rallway, and Jefirey H. Bartlett, Westfield, N. J., assignors to Esso Research and Engineering Company, acorporation of Delaware Application February 2, 1953, Serial No 334,717

11 Claims. (Cl. 252-33.6)

No Drawing.

The present invention relates to an improved method of preparinglubricating greases and to grease compositions produced by this method.More specifically, the invention pertains to improvements in themanufacture of grease thickeners and to greases containing suchthickeners. In its broadest aspect, the invention provides an improvedmethod of preparing amino acids and grease thickeners by fusing highmolecular weight amino derivatives having a primary alcohol group,particularly amino ether alcohols, with caustic alkali, producing ametal soap from the amino acid so formed and incorporating this metalsoap into a lubricating oil in grease making proportions. In a preferredembodiment of the invention, the fusion is carried out in the presenceof lubricating oil.

Lubricating greases normally consist of lubricating oils thickened byalkali and alkaline earth metal soaps or other thickeners to a solid orsemi-solid consistency. The soaps may be prepared by the neutralizationof high molecular Weight fatty acids or by the saponification of fatswhich is usually carried out in a portion of the oil to be thickened.

The present invention pertains to highly valuable, stable lubricatinggreases in which the high molecular weight fatty acids are replaced orat least supplemented by a new grease making material. It has now beenfound that such greasesmay be prepared by incorporating into lubricatingoils a grease thickener obtained by fusing high molecular weight aminoderivatives having. a primary alcohol group, particularly amino etheralcohols, with alkali, particularly caustic soda or potash attemperatures of about 400620 F., preferably about 500-575 F. fora timesufiicient to form the alkali metal salt ofthe acid corresponding to theamino alcohol used. The chemical reaction taking place during the fusionprocess may be illustrated by the following equation:

E- CHzCI-IzOH-l-MOH 2Hz-l-E- CHzCOOM (1) wherein E may be an amino or anamino ether radical containing 1 or more carbon atoms and M is an alkalimetal, such as sodium or potassium. The amino or amino ether alcoholshould contain a total of at least carbon atoms per molecule.

The discovery of the utility of alkali fusion of high molecular weightamino alcohols for grease making greatly increases the Wealth of rawmaterials available for grease production. Heretofore, ester-type fats,oils or high molecular Weight fatty acids have been used almostexclusively in the manufacture of soap-thickened greases and thesestarting materials have been believed indispensable for the purpose. Allthese materials have numerous other industrial uses, a situationconducive to the development of shortages forcing undesirable variationsin grease making procedures and grease characteristics. The discovery ofan entirely new and large class of suitable raw materials cases thissituation considerably.

The use of high molecular weight amino alcohols as grease makingmaterials introduces no complication into the grease making procedure.While alkali fusion of the ice amino alcohol may be carried out in aseparate preliminary acid-forming stage, the greases are preferablyproduced essentially in a single process step in which the highmolecular weight amino alcohol is fused with alkali in the lubricatingoil base in greasemaking proportions and atgrease making conditions,although at somewhat higher temperatures. At the conclusion of thefusion process a finished grease is obtained.

Quite generally, amino alcohols, particularly amino ether alcohols, maybe used which have about 10-50 or,

more carbon atoms per molecule and a s'utficiently high boiling point toprevent excessive volatilization during the fusion process. The aminoalcohols suitable for the invention have the general formula and yieldupon alkali fusion ether acids of the formula wherein R=a hydrocarbongroup containing from 1-40 carbon atoms selected from the groupconsisting of alkyl, alkylene, naphthenyl, aryl, alkaryl and aralkyl Rand R: H or one of the groups represented by R y=an integer from 0-50x=0 or 1, z=l or 2, and x+z=2.

These amino alcohols include the amino derivatives of alkylene orpolyalkylene (e. g. ethylene, propylene, polyethylene, polypropylene)glycols. Specific examples of these compounds are:

TYPE B R-N- (C HO H2- O) ,C H-CH OH monoalkylamino alkoxy i alkanol H IIRI I or monoalkylamlno alkanol =alkylamino bis (alkoxy alkanol) oralkylamino bis alkanol Examples:

Monoethylamino-decapropoxypropanol Monolaurylaminooctadecapropoxydodecaethoxyi ethanol Mono-coco-amino-eicosaethoxyethanol Mono-stearylamino-ethanolToluino-pentadecaethoxyethanol TYPE C R.N-(CH-C Hz-O) OE-43H; OH=dialkylamino alkoxy alkanol I R V I RI! or dialkylamlno alkanol perivedfrom mon0-cocoamine made by reduction of the nitnles of cocoanut oilacids.

Patented Aug. 6, 1957? 3 Examplesi Diethylamino-pentadecaethoxyethanolDioctylaminodecaethoxyethanol Octyl laurylamino-decaethoxyethanolDiphenylamino-triacontaethoxyethanol Dicetylamino-tetraethoxyethanolDilaurylaminodipropoxypropanol Di-coco-amino ethanol Di-coco-aminopentapropoxydiethoxyethanol Di coco amino---triethoxydipropoxytetraethoxyethanol Didodecylamino-ethanolParticularly desirable starting materials are the amino and amino etheralcohols obtained from primary or secondary aliphatic amines,particularly straight chain amines, such as octadecyl amine, laurylamine, etc.

"The amino and amino ether alcohols to be subjected to alkali fusion inaccordance with the invention may be prepared from these startingmaterials quite generally by a reaction with alkylene oxides, such asethylene oxide, propylene oxide, butylene oxide, nonylene oxide,hexadecene oxide, butadiene monoxide, styrene monoxide, etc., attemperatures of about 2l2 F. in the presence or absence of catalysts,for example an alkaline type catalyst, to form monoglycol or polyglycolethers having a primary alcohol group. The amount of alkylene oxide usedmay be as high as 50 or more mols for each mol of the amino compoundused as the starting material.

The water and oil solubility of this end product may be controlled to acertain degree by a proper choice of the molecular Weight of thealkylene oxide used. In general, the higher the molecular weight of thealkylene oxide the lower the water solubility and the higher the oilsolubility of theend product. Thus, water insoluble, oil soluble endproducts may be produced by combining the low molecular weight aminocompounds with high molecular weight alkylene oxides.

The reactions involved in the formation of suitable amino alcohols fromamino compounds and alkylene oxides may be illustrated by the followingequations: R-IFH (11-1-1) R"-CHCH2 The amino or amino ether alcoholsproduced in this manner may then be converted into the correspondingcarboxylic acids or their soaps by fusion with alkali as described aboveand illustrated with reference to Equation 1. While the acids and soapsmay be produced in a separate process step and the preformed productsincorporated into lubricating oils in grease making proportions, aparticular advantage of the present invention resides in the factthatthe new grease thickeners may be prepared in situ in the lubricatingoil as an integral stage of the grease making process. In other words,the amino alcohols may be converted into soaps by alkali fusion in'thegrease kettle using the lubricating oil base of the grease as a reactionmedium.

When carrying out this preferred embodiment of the invention, it hasbeen observed that the alkali has a strong tendecy to settle out of thereaction mixture to the bottom of the reactor in the form of a cakewhich does not fully participate in the reaction. Highly efiicientstirring or agitation will counteract this tendency. However, in manycases more efficient stirring is required than may be obtained inconventional grease kettles and special equipment is necessary.

This settling tendency of the alkali in the lubricating oilamino alcoholmixture is negligible when a sufficient amount of a solid suspendingagent is present in the reaction mixture. Most desirable suspendingagents are those which serve simultaneously as grease thickeners, suchas soaps of high molecular weight fatty acids, silica gel, carbon black,bentones, Attapulgus clay modifications, etc.

Soaps, particularly sodium soaps of high molecular Weight fatty acids,are preferred for this purpose. Howin accordance with a speclficembodiment of the invention by using the salt, preferably the alkalimetal salt, of a low molecular weight acid in addition to the highmolecular weight fatty acid soap. In this manner, soapsalt complexes areformed which melt well above 500 F. and thus form an excellentsuspending agent.

These soaps or soap-salt complexes are preferably formed in situ byneutralization of the corresponding acids in the amino alcohol-oilmixture with alkali added in amounts sufficient ,for this neutralizationand the subsequent fusion which takes place at considerably highertemperatures. High molecular weight acids useful for this purposeinclude hydrogenated fish oil acids, C1z-Cz2 naturally occurring acidsof animal or vegetable origin, etc. These acids may be used in amountsranging from about 2-30 wt. percent based on the finished product.Suitable low molecular weight acids include acetic, furoic, acrylic andsimilar acids to be used in proportions of about 1-10 wt. percent basedon the finished product. Esters, e. g. glycerides of the high and/or lowmolecular weight acids, particularly those containing mono basic acidesters may be used in place of the free acids in correspondingproportions. In this case, the alcohol portions of the esters areconverted into acids and the corresponding soaps by alkali fusion. Ifesters of low molecular weight alcohols are used, elevated pressures maybe employed to prevent volatilization of the alcohols. Of course, estersof nonvolatile low molecular weight alcohols, such as polyhydroxyalcohol esters, e. g. sorbitol acetate, glycol acetate, etc., may beused. Particularly the high molecular weight type of acids or theiresters used for this purpose may also be prepared by alkali fusion ofamino alcohols. In this case, a portion of the product of the alkalifusion process in which the principal grease thickener is prepared inaccordance with the invention may be returned to the fusion stage toserve as an agent preventing settling of the alkali.

Soaps of high molecular Weight fatty acids and/or soap-salt complexes ofthe type specified may be incorporated in the greases of the presentinvention to improve high temperature or other characteristics even ifno suspending agents are required. Thus, when soaps derived frombranched-chain amino alcohols are employed it is often desirable toincorporate soaps derived from straight-chain fatty acids in order toobtain greases having particular structure characteristics.

The soaps formed by alkali fusion of amino alcohols in the presence ofother fatty acid soaps yield excellent smooth greases. Otherconventional thickeners, antioxidants, corrosion inhibitors, tackinessagents, loadcarrying compounds, viscosity index improvers, oilinessagents, and the like may be added prior, during and/ or after the fusionprocess as will be apparent to those skilled in the art.

The'base oil used as rnenstruum during the fusion process should'be amineral lubricating oil. After the fusion is completed, syntheticlubricating oils, such as a dibasic acid ester (e. g. di-Z-ethyl hexylsebaca te, adipate, etc.), polyglycol type synthetic oils, esters ofdibasic acids and polyhydric alcohols, etc, as well as alkylsilicates,--carbonates, formals, acetals, etc., may be This difiicultymay be overcome;

.="alkali per mol of amino alcohol.

. t used alone or in addition to mineral lubricating oil to bring thegrease to the desired consistency. The oil base preferably comprisesabout 50 to about 95% of the total weight of the finished grease.

. As indicated above, the alkali fusion of the invention may becarriedout in two stages. When so operating,

theamino alcohol to be fused may be added in the initial charge or overa period of 1-8 hours to a molten rrliixture of alkali and mineral oil,maintained atfusion tegrnperatures of, 'say, about 400-620 F. The amountof alkali employed may be substantially stoichiometric hr somewhathigher, for example from 1-3 mols of When all the amino alcohol has beenadded, heating may be continued at these temperatures until 1 gasevolution substantially ceases. The acid formed may be recovered fromthe reaction mixture after cooling, by dilution with water or with 50%isopropanol, followed by extraction of the oil and any unreacted alcoholwith a suitable solvent,

such as heptane or the like, and acidification. If desired, the freeacid may be purified by vacuum distillation.

The acid so prepared may then be introduced into a alkali, preferably inaqueous solution, to neutralize the acids present. Conventional greasemaking conditions including temperatures of about 350-500 F. may be usedin this stage. The soap derived from the amino alcohol by alkali fusionshould form at least wt. percent and preferably about -50 wt. percent ofthe grease thickener or about 20-20 wt. percent of the finished grease.is preferably made up by a suitable soap-salt complex of the typedescribed above. The proportion of soap derived from amino alcohol tosoaps and salts derived from other acids may be about 1:4 to 4:1 andpreferably is about 1:1. i

The free amino polyether acids and also their soaps may be used asadditives in lubricating oils. By controlling the length of the alkylgroup and the polyether groups, the resulting acids may be valuable inthe production of oil soluble chelates and the soaps may be valuable asdetergents. A

In order to prepare a grease by alkali fusion of the amino alcohol insitu in accordance with a more desirable embodiment of the invention,procedure may be quite generally as follows. A mineral lubricating oilbase is mixed with the amino alcohol and the mixture is heated to about130-180 F.

The alkali is added preferably in the form of an aqueous solution ofabout 3050% concentration. The mass is then dehydrated at temperaturesof about 300-400 F. for about 1-6 hours, depending upon the size of thebatch. Thereafter, the temperature is increased to a fusion temperatureof about 400-620 F. and maintained within this range until gas formationhas receded appreciably, which takes place usually after about 1-2hours. The grease may then be allowed to cool under stirring to about200 250 F. at which level further additives may be introduced. Finally,the grease may be poured into pans to be cooled to room temperature.

A similar procedure is employed when the amino alcohol is subjected toalkali fusion in situ in the pres ence of suspending agents, such assoaps of high mo- 'lecular weight fatty acids or complexes of such soapswith salts of low molecular weight acids in accordance with thepreferred embodiment of the invention. In

The remainder of the grease thickener the grease making.

this case, the high molecular weight acids are added to the mineral oiltogether with the amino alcohol while the low molecular weight acid maybe added after the initial heating stage immediately prior to. thealkali addition.

Thereafter, sufficient caustic alkali to neutralize the acids 6. andconvert the amino alcohol to soap is added, preferably in the form of anaqueous solution of about 40-50% and the mixture is heated at a.saponification temperature of about 300 400 F. until the acids areconverted to soaps and salts and all the water is volatilized. Alkalifusion is then carried out substantially as described above, except thatless violent stirring is required.

The invention will be best understood by reference to the followingspecific examples which represent preferred modifications of theinvention.

Example I Dicocoaminoethanol having the formula N-GHz-CHzOH (averagemolecular weight approximately 425) was prepared by reacting ethyleneoxide with dicocoamine manufactured by Armour and Company by reductionof the nitriles of coconut oil acids. The dicocoaminoethanol was used ingrease manufacture as follows:

1 Hydrogenated-fish oil acids, having a degree of unsaturationcorresponding approximately to commercial stearic acid.

PREPARATION The dicocoaminoethanol, the Hydrofol acids 54 and /2 of themineral oil were charged to a fire heated kettle equipped with means ofgood agitation. The ingredients were warmed to 170 F. and the aceticacid. was charged thereto, followed immediately by a 40% aqueoussolution of the sodium hydroxide. Heating was continued at 400 F. untilthe mixture was dehydrated. The balance of the mineral oil was added andheating continued to 560 F. At this temperature a suddenlarge expansionin the kettle contents occurred, which slowly subsided. Heating at 560F. was continued for minutes. The grease was solid at this temperatureHeating was discontinued but stirring continued while cooling to 250 F.wherethe phenyl alpha-naphthylamine was added. Cooling was thencontinued to 200 F. Properties:

Dropping point, F 500+. Penetration, mm./10; 77 F:

Unworked 136. Worked 60 strokes 160. Worked 100,000 strokes Waterwashing test, per- 1 cent loss Norma Hoifmann oxidation test, hours to 5p. s. i. Drop in oxygen pressure Appearance None.

Excellent smooth uniform 7 Example II the aai ae assi t ssssl i2 thi asnsta Eth meea 17 a 259W; 9?? A .1 @1251. @qitipans li q ae n "W in? heBRSQ I ta genera ormu a (9191 E: It st nds, for a h drocarbon raaldesired. iit talle and con sti g o b u saturated C16 groups, 70%,saturated Q1}; groups and 5% unsaturated C18 groups. This amino alcoholis made by reacting tallow acids with ammonia to form the ammonium Saltt these ear s heatin t9. dehydrate the sa to the amide, furtherdehydrating the latter to form the nitrile, reducing the nitrile to theamine and reacting this amine with ethylene oxide per mol of amine.

Ingredients: Weight percent .rli liylaaiias t H Blend of nap "nic typemineral oil distillate having a viscosity of 55 S. S. U. at 210 FL-68.50

PREPARATION Th Hydrofol i s ,.Et119mea li. and. 4 he, miIiTI-IaI'5i'1V5i5h S'UQ afii t h ated; rea ke tl war'md to l SO FI aceticacid,was;added, fol;- lo'w'ed immediateIybyYaAQWO agueous solution ofNaOH; The temperature was raised to 400 E., volatilizing water. iil l heama he netal;q li asadd d at g wascontinued to- 560--F-. and: thetemperature heldabove 500 F. for 2 hours. Then heatingwas discontinuedand the mass allowed to cool while agitating. When a temperature of275-f was reachedl' the inhibitor (phenyl alphaY- naphthylamine wasadded and the mass I cooled to throughaliomogeuiier, filteredfandpackaged. ress? Dropping point F 500+ Penetrations, 77- F.- mm./ 10:

Unwor ked- 199- Worked- 60 strokes 7 Worked 60,;000 strokes Water.washing test, percent loss None;

=b 1a1 qPfi=fih-. isasa sft ii-t e ket l s ilu e as follows? 50% abovedescribed product 50% solvent extracted Mid-Conti-nentdistillate+solvent Q extracted Bright Stock, havinga viscosity of 57' S.S; U. at 210 F. and a V. I.=' 0f;102.*

This product was homogeniged, filtered and packaged.

Properties:

Dropping point, F 47.2 Penetrations, 77 F. mm./10.! v

Unworked 310 Worked 60 strokes 320 Worked 100,000 strokes 33,2

Water; a i-ngtes per e t 0 Q n in. pxxsenp e surs 214 The invention isnot limited to theaspeoific figures of wherein R is. an alkylhydrocarbon group containing fronzi l carbon atoms, 3! is an integerfrom 0-50,v x is at;

integer from. 0 to 1, z is an integer from 1 to 2, and

grease thickner is made up of, about 30 to wt. percent of the alkalimetal soap derived from the amino alcohol,. and the remainder is made upof an alkali metal soap of a high molecular weight fattyacid.

3. A grease according to. claim 1, wherein said grease thickener is madeup of. about 30 to 50 wt. percent oithe alkali metal soap derivedfrom:the amino alcohol. and the remainder is-made up of: a complex of. a:high molecular Weight fatty acid soap with a low molecular Weight fattyacid salt;

4. Agrease according to-claim: l. which containsa minor amount ofasuspending agent, whichis solid at the: conditiqns of fusion,suflicientitoprevent the alkali fI01'nS6ttling; out; of the:reactionlmixture during said fusion.

5 A; grease according; to; claim=1 in which. said alcohol has. thegeneral: formula,

6; Agreaseaccording-toyclaim- 1; in which" said: alcohol aSal'ttaeneral. formula 7.- The-process: of preparing a a: lubricating; greasecom position which comprises admixing a major proportion'of. a minerallubricating; oilgwith; an. amino. alcohol having about 101050,carbon-atoms; per; molecule and having. he general. formula,

wherein Ris an alkylhydroearbon group. containing from carbon atom s,,yis.,an integer. from 0 5 0;,x is.an integer from 0j toll, zuis anintegerfrom'1.to.2,.andx+ z is 2, heating saidmixturento a-temperature ofabout130to 180 Ff, then adding ,an. amount ofialkalisufli cienttorfusing saidjaminotaljcohol, dehydrating theresulting mixtureata temperatu-reofabout300"to 400F'.,.. continuing heating at a temperature off about 400 to620TF'. until gas evolution substantially ceases and-Jth'en cooling theresulting grease composition, said amino. alcohol being employ ed inanamount sufficientto form about 2",to 20;;wt.. p ercent, of'a greasethick'eningalkali" metal soap 8: The process for preparing lubricatinggrease compositions, which comprises admixing a major proportion of amineral lubricating oil, about 2 to,30 wt. percent, based on thefinished grease composition, ofla high molecular weight fatty acid andan amino alcohol having about 10" to 50carbon atoms per molecule andhaving thegeneral formula 2, hea-tin'g 'saidrniXture -to a temperatureof about 130 10 adding to the heated mixtureeabout 1 "to 10%"- A re seaccording to claim 1 wherein the said by weight; based on the finished"grease cornposition tof-a ent alkali for fusing said amino alcohol andfor nutralizing said high and low molecular weight carboxylic acids,dehydrating the resulting mixture at a temperature of about 300 to 400F., continuing heating at a temperature of about 400 to 620 F. until gasevolution substantially ceases and then cooling the resulting greasecomposition, said amino alcohol being employed in an amount suflicientto form about 2 to 20 wt. percent of a grease-thickening alkali metalsoap.

9. The process of claim 8 wherein the high molecular weight/fatty acidis a hydrogenated fish oil acid and said low molecular weight carboxylicacid is acetic acid.

10. The process of claim 8 wherein said amino alcohol is dicocoaminoethanol.

11. The process of claim 9 wherein said amino alcohol has a molecularweight of 491 and the approximate formula CHIOH2Oh-B wherein R is ahydrocarbon radical of tallow acid.

References Cited in the file of this patent UNITED STATES PATENTSKokatnur Apr. 24, 1928 Reid May 3, 1932 Pelton et a1 Sept. 12, 1933Strosacker et a1 Sept. 12, 1933 Strosacker et al. Nov. 7, 1933 WilmannsFeb. 14, 1939 Platz et al. July 4, 1939 Haussmann et a1 Dec. 19, 1939Stephenson et a1 Apr. 9, 1940 Kokatnur Aug. 20, 1940 Curme et al Sept.18, 1945 Chitwood Sept. 18, 1945 Curme et al Sept. 18, 1945 Billman Jan.6, 1948 Bryant eta]. July 22, 1952 Bryant June 2, 1953

1. A LUBRICATING GREASE COMPRISING A LUBRICATING OIL AND A GREASE MAKINGPROPORTION OF A GREASE THICKENER COMPPRISING AN ALKALI METAL SOAP OF ANORGANIC ACID PRODUCED BY FUSING AN AMINO ALCOHOL WITH ALKALI AT ATEMPERATURE IN THE RANGE OF 400 TO 620* F. UBTIL GAS EVELUTIONSUBSTANTIALLY CEASES, SAID ALCOHOL HAVING ABOUT 10 TO 50 CARBON ATOMSPER MOLECULE AND HAVING THE GENERAL FORMULA